Very impressive tank.
When helping set up my girlfriends African tank recently we just went to a few lfs, looked at the Malawi Cichlids that were available and picked ones she liked the look of. Could you not try the same? Don't know if cross breeding will/would be a problem but at least you could make sure you pick fish you like the colour of, and lots of them! (yellow labs are always a winner)
As for the bottom, also gone for a small group of clown loaches for even more colour, and a couple of plecos and synos. can't see why the same wouldn't work for you but on a much larger scale.
I don't know what mid level schooling fish would work with africans, but if you had a lot of Clown Loaches would that not count as the School?
Look forward to seeing the end result.
Back onto the rather impressive tank, is the bottom one large piece of glass or how is it made?